Correlation study between facet joint cartilage and intervertebral discs in early lumbar vertebral degeneration using T2, T2* and T1ρ mapping

Abstract

Recent advancements in magnetic resonance imaging have allowed for the early detection of biochemical changes in intervertebral discs and articular cartilage. Here, we assessed the feasibility of axial T2, T2* and T1ρ mapping of the lumbar facet joints (LFJs) to determine correlations between cartilage and intervertebral discs (IVDs) in early lumbar vertebral degeneration. We recruited 22 volunteers and examined 202 LFJs and 101 IVDs with morphological (sagittal and axial FSE T2-weighted imaging) and axial biochemical (T2, T2* and T1ρ mapping) sequences using a 3.0T MRI scanner. IVDs were graded using the Pfirrmann system. Mapping values of LFJs were recorded according to the degeneration grades of IVDs at the same level. The feasibility of T2, T2* and T1ρ in IVDs and LFJs were analyzed by comparing these mapping values across subjects with different rates of degeneration using Kruskal-Wallis tests. A Pearson’s correlation analysis was used to compare T2, T2* and T1ρ values of discs and LFJs. We found excellent reproducibility in the T2, T2* and T1ρ values for the nucleus pulposus (NP), anterior and posterior annulus fibrosus (PAF), and LFJ cartilage (intraclass correlation coefficients 0.806–0.955). T2, T2* and T1ρ mapping (all P<0.01) had good Pfirrmann grade performances in the NP with IVD degeneration. LFJ T2* values were significantly different between grades I and IV (PL = 0.032, PR = 0.026), as were T1ρ values between grades II and III (PL = 0.002, PR = 0.006) and grades III and IV (PL = 0.006, PR = 0.001). Correlations were moderately negative for T1ρ values between LFJ cartilage and NP (rL = −0.574, rR = −0.551), and between LFJ cartilage and PAF (rL = −0.551, rR = −0.499). T1ρ values of LFJ cartilage was weakly correlated with T2 (r = 0.007) and T2* (r = −0.158) values. Overall, we show that axial T1ρ effectively assesses early LFJ cartilage degeneration. Using T1ρ analysis, we propose a link between LFJ degeneration and IVD NP or PAF changes.

T2* Mapping of the Adult Intervertebral Lumbar Disc: Normative Data and Analysis of Diurnal Effects

“…In comparison to our observation, they observed relatively high T2* values in the anterior AF (T2* = 70.7 ± 75.4 ms) and posterior AF (T2* = 30.7 ± 11.3 ms) in IVDs with Pfirrmann grade I while their T2* values in the NP (T2* = 63.8 ± 26.8 ms) were similar to ours. Zhang et al studied the correlation of facet joint cartilage degeneration and IVD degeneration in a study cohort of 22 healthy, adult volunteers with nonspecific acute LBP (mean age: 33.2 years ranging from 21 to 44 years) using T2‐, T2*‐, and T1ρ‐mapping in the axial plane. The mean T2* values in normal appearing discs (Pfirrmann grade I) were 79.16 ± 10.22 ms in the NP, 30.97 ± 7.51 ms in the anterior AF and 34.15 ± 5.82 ms in the posterior AF.…”

“…Various studies have attempted to investigate the qualitative and quantitative properties of the IVD via biochemically sensitive magnetic resonance imaging (MRI) that includes GagCEST (glycosaminoglycan chemical exchange saturation transfer), dGEMRIC (delayed gadolinium‐enhanced MRI), T1rho, sodium and T2 mapping . The present study uses the T2* mapping technique, a method that is comparable to T2 mapping MRI, which has been proven feasible on human and animal samples, in vitro and in vivo in the lumbar and cervical spine . T2* mapping is implementable on all routine 1.5 and 3 T MRI systems, requires a relatively short acquisition time and allows for high image‐resolution and three‐dimensional (3D) imaging …”

“…Considering previous studies, we expected a topographical T2* profile of the disc with higher values in the nucleus, compared to the annulus fibrosus (AF), and segmental differences of the discs in physiologically different strained spinal regions. In addition, a sufficient number of T2* measurements of the lumbar spine are unavailable for young, healthy, adult subjects under the auspices of what one would call “normative data” as the previous studies mainly examined patients with vertebral problems or cadaveric human or animal spines . The present study aimed to identify potential diurnal effects and to generate T2* mapping baseline values in a sufficient cohort of young healthy, adult subject, aiming to establish possible benchmark (normative data) for future studies and evaluations taking zonal and segmental differences into account.…”

Comprehensive assessment of in vivo lumbar spine intervertebral discs using a 3D adiabatic T1ρ prepared ultrashort echo time (UTE-Adiab-T1ρ) pulse sequence

“…Many studies have demonstrated that quantitative T 1ρ mapping is a promising technique for detecting biochemical changes in IVDs during the process of degeneration (14)(15)(16)(17)(18). To date, research on T 1ρ measurements of IVDs has focused on changes in the NP (16,(18)(19)(20)(21)(22), and the AF (20)(21)(22). The CEP may be degraded, affecting nutrient availability and cell metabolism in the remainder of the IVD and, thus, contribute to degeneration of the NP and AF (9).…”

“…modified Pfirrmann grade may reflect loss of proteoglycans during the process of degeneration(18)(19)(20)(21).…”